添加致谢页

src/include/Tetris.h

@@ -227,6 +227,9 @@ extern Point target;
 extern MenuState menuState;
 extern HelpState helpState;
 extern int helpScrollOffset;
+extern int creditPageIndex;
+extern int creditAnimationTicks;
+extern int creditAnimationDirection;
 extern int upgradeListScrollOffset;
 extern PlayerStats classicStats;
 extern PlayerStats rogueStats;
@@ -267,6 +270,8 @@ void ReturnToMainMenu();
 void ReviveAfterVideo();
 void SetFeedbackMessage(const TCHAR* title, const TCHAR* detail, int ticks);
 void OpenRulesScreen();
+void OpenCreditScreen();
+void ChangeCreditPage(int direction);
 void OpenUpgradeMenu();
 void ConfirmUpgradeSelection();
 void ResetUpgradeUiState();
@@ -277,6 +282,7 @@ void UseAirReshape();
 void ResetPendingRogueVisualEvents();
 void ResetVisualEffects();
 bool TickVisualEffects();
+bool TickCreditAnimation();
 void TriggerLineClearEffect(const int* rows, int rowCount, int linesCleared);
 void PlayPendingLineClearEffect();
 void TriggerCellClearEffect(const Point* cells, int cellCount, bool strongBurst);